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                    程序结构
            
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                    类型
            
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                    常量
            
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                    结构体
            
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                    JSON
            
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                    文本和HTML模板
            
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                    函数
            
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                    函数值
            
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                    匿名函数
            
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                    可变参数
            
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                    Deferred函数
            
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                    Panic异常
            
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                    Recover捕获异常
            
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                    方法
            
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                    方法声明
            
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                    基于指针对象的方法
            
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                    通过嵌入结构体来扩展类型
            
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                    方法值和方法表达式
            
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                    示例: Bit数组
            
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                    封装
            
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                    接口
            
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                    接口是合约
            
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        <li class="chapter " data-level="1.8.2" data-path="ch7-02.html">
            
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                    接口类型
            
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                    实现接口的条件
            
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                    flag.Value接口
            
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                    接口值
            
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                    sort.Interface接口
            
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                    http.Handler接口
            
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                    error接口
            
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                    示例: 表达式求值
            
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                    类型断言
            
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        <li class="chapter " data-level="1.8.11" data-path="ch7-11.html">
            
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                    基于类型断言识别错误类型
            
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                    通过类型断言查询接口
            
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        <li class="chapter " data-level="1.8.13" data-path="ch7-13.html">
            
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                    类型分支
            
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                    示例: 基于标记的XML解码
            
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                    补充几点
            
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        <li class="chapter " data-level="1.9" data-path="../ch8/ch8.html">
            
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                    Goroutines和Channels
            
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                    Goroutines
            
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        <li class="chapter " data-level="1.9.2" data-path="../ch8/ch8-02.html">
            
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                    示例: 并发的Clock服务
            
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        <li class="chapter " data-level="1.9.3" data-path="../ch8/ch8-03.html">
            
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                    示例: 并发的Echo服务
            
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                    Channels
            
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        <li class="chapter " data-level="1.9.5" data-path="../ch8/ch8-05.html">
            
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                    并发的循环
            
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        <li class="chapter " data-level="1.9.6" data-path="../ch8/ch8-06.html">
            
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                    示例: 并发的Web爬虫
            
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        <li class="chapter " data-level="1.9.7" data-path="../ch8/ch8-07.html">
            
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                    基于select的多路复用
            
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                    示例: 并发的目录遍历
            
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                    并发的退出
            
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                    示例: 聊天服务
            
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        <li class="chapter " data-level="1.10" data-path="../ch9/ch9.html">
            
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                    基于共享变量的并发
            
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                    竞争条件
            
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        <li class="chapter " data-level="1.10.2" data-path="../ch9/ch9-02.html">
            
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                    sync.Mutex互斥锁
            
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        <li class="chapter " data-level="1.10.3" data-path="../ch9/ch9-03.html">
            
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                    sync.RWMutex读写锁
            
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                    内存同步
            
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                    sync.Once惰性初始化
            
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        <li class="chapter " data-level="1.10.6" data-path="../ch9/ch9-06.html">
            
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                    竞争条件检测
            
                </a>
            

            
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        <li class="chapter " data-level="1.10.7" data-path="../ch9/ch9-07.html">
            
                <a href="../ch9/ch9-07.html">
            
                    
                    示例: 并发的非阻塞缓存
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.10.8" data-path="../ch9/ch9-08.html">
            
                <a href="../ch9/ch9-08.html">
            
                    
                    Goroutines和线程
            
                </a>
            

            
        </li>
    

            </ul>
            
        </li>
    
        <li class="chapter " data-level="1.11" data-path="../ch10/ch10.html">
            
                <a href="../ch10/ch10.html">
            
                    
                    包和工具
            
                </a>
            

            
            <ul class="articles">
                
    
        <li class="chapter " data-level="1.11.1" data-path="../ch10/ch10-01.html">
            
                <a href="../ch10/ch10-01.html">
            
                    
                    包简介
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.11.2" data-path="../ch10/ch10-02.html">
            
                <a href="../ch10/ch10-02.html">
            
                    
                    导入路径
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.11.3" data-path="../ch10/ch10-03.html">
            
                <a href="../ch10/ch10-03.html">
            
                    
                    包声明
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.11.4" data-path="../ch10/ch10-04.html">
            
                <a href="../ch10/ch10-04.html">
            
                    
                    导入声明
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.11.5" data-path="../ch10/ch10-05.html">
            
                <a href="../ch10/ch10-05.html">
            
                    
                    包的匿名导入
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.11.6" data-path="../ch10/ch10-06.html">
            
                <a href="../ch10/ch10-06.html">
            
                    
                    包和命名
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.11.7" data-path="../ch10/ch10-07.html">
            
                <a href="../ch10/ch10-07.html">
            
                    
                    工具
            
                </a>
            

            
        </li>
    

            </ul>
            
        </li>
    
        <li class="chapter " data-level="1.12" data-path="../ch11/ch11.html">
            
                <a href="../ch11/ch11.html">
            
                    
                    测试
            
                </a>
            

            
            <ul class="articles">
                
    
        <li class="chapter " data-level="1.12.1" data-path="../ch11/ch11-01.html">
            
                <a href="../ch11/ch11-01.html">
            
                    
                    go test
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.12.2" data-path="../ch11/ch11-02.html">
            
                <a href="../ch11/ch11-02.html">
            
                    
                    测试函数
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.12.3" data-path="../ch11/ch11-03.html">
            
                <a href="../ch11/ch11-03.html">
            
                    
                    测试覆盖率
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.12.4" data-path="../ch11/ch11-04.html">
            
                <a href="../ch11/ch11-04.html">
            
                    
                    基准测试
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.12.5" data-path="../ch11/ch11-05.html">
            
                <a href="../ch11/ch11-05.html">
            
                    
                    剖析
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.12.6" data-path="../ch11/ch11-06.html">
            
                <a href="../ch11/ch11-06.html">
            
                    
                    示例函数
            
                </a>
            

            
        </li>
    

            </ul>
            
        </li>
    
        <li class="chapter " data-level="1.13" data-path="../ch12/ch12.html">
            
                <a href="../ch12/ch12.html">
            
                    
                    反射
            
                </a>
            

            
            <ul class="articles">
                
    
        <li class="chapter " data-level="1.13.1" data-path="../ch12/ch12-01.html">
            
                <a href="../ch12/ch12-01.html">
            
                    
                    为何需要反射?
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.13.2" data-path="../ch12/ch12-02.html">
            
                <a href="../ch12/ch12-02.html">
            
                    
                    reflect.Type和reflect.Value
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.13.3" data-path="../ch12/ch12-03.html">
            
                <a href="../ch12/ch12-03.html">
            
                    
                    Display递归打印
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.13.4" data-path="../ch12/ch12-04.html">
            
                <a href="../ch12/ch12-04.html">
            
                    
                    示例: 编码S表达式
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.13.5" data-path="../ch12/ch12-05.html">
            
                <a href="../ch12/ch12-05.html">
            
                    
                    通过reflect.Value修改值
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.13.6" data-path="../ch12/ch12-06.html">
            
                <a href="../ch12/ch12-06.html">
            
                    
                    示例: 解码S表达式
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.13.7" data-path="../ch12/ch12-07.html">
            
                <a href="../ch12/ch12-07.html">
            
                    
                    获取结构体字段标签
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.13.8" data-path="../ch12/ch12-08.html">
            
                <a href="../ch12/ch12-08.html">
            
                    
                    显示一个类型的方法集
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.13.9" data-path="../ch12/ch12-09.html">
            
                <a href="../ch12/ch12-09.html">
            
                    
                    几点忠告
            
                </a>
            

            
        </li>
    

            </ul>
            
        </li>
    
        <li class="chapter " data-level="1.14" data-path="../ch13/ch13.html">
            
                <a href="../ch13/ch13.html">
            
                    
                    底层编程
            
                </a>
            

            
            <ul class="articles">
                
    
        <li class="chapter " data-level="1.14.1" data-path="../ch13/ch13-01.html">
            
                <a href="../ch13/ch13-01.html">
            
                    
                    unsafe.Sizeof, Alignof 和 Offsetof
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.14.2" data-path="../ch13/ch13-02.html">
            
                <a href="../ch13/ch13-02.html">
            
                    
                    unsafe.Pointer
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.14.3" data-path="../ch13/ch13-03.html">
            
                <a href="../ch13/ch13-03.html">
            
                    
                    示例: 深度相等判断
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.14.4" data-path="../ch13/ch13-04.html">
            
                <a href="../ch13/ch13-04.html">
            
                    
                    通过cgo调用C代码
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.14.5" data-path="../ch13/ch13-05.html">
            
                <a href="../ch13/ch13-05.html">
            
                    
                    几点忠告
            
                </a>
            

            
        </li>
    

            </ul>
            
        </li>
    
        <li class="chapter " data-level="1.15" data-path="../appendix/appendix.html">
            
                <a href="../appendix/appendix.html">
            
                    
                    附录
            
                </a>
            

            
            <ul class="articles">
                
    
        <li class="chapter " data-level="1.15.1" data-path="../appendix/appendix-a-errata.html">
            
                <a href="../appendix/appendix-a-errata.html">
            
                    
                    附录A：原文勘误
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.15.2" data-path="../appendix/appendix-b-author.html">
            
                <a href="../appendix/appendix-b-author.html">
            
                    
                    附录B：作者译者
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.15.3" data-path="../appendix/appendix-c-cpoyright.html">
            
                <a href="../appendix/appendix-c-cpoyright.html">
            
                    
                    附录C：译文授权
            
                </a>
            

            
        </li>
    
        <li class="chapter " data-level="1.15.4" data-path="../appendix/appendix-d-translations.html">
            
                <a href="../appendix/appendix-d-translations.html">
            
                    
                    附录D：其它语言
            
                </a>
            

            
        </li>
    

            </ul>
            
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                                <h2 id="71-&#x63A5;&#x53E3;&#x7EA6;&#x5B9A;">7.1. &#x63A5;&#x53E3;&#x7EA6;&#x5B9A;</h2>
<p>&#x76EE;&#x524D;&#x4E3A;&#x6B62;&#xFF0C;&#x6211;&#x4EEC;&#x770B;&#x5230;&#x7684;&#x7C7B;&#x578B;&#x90FD;&#x662F;&#x5177;&#x4F53;&#x7684;&#x7C7B;&#x578B;&#x3002;&#x4E00;&#x4E2A;&#x5177;&#x4F53;&#x7684;&#x7C7B;&#x578B;&#x53EF;&#x4EE5;&#x51C6;&#x786E;&#x7684;&#x63CF;&#x8FF0;&#x5B83;&#x6240;&#x4EE3;&#x8868;&#x7684;&#x503C;&#xFF0C;&#x5E76;&#x4E14;&#x5C55;&#x793A;&#x51FA;&#x5BF9;&#x7C7B;&#x578B;&#x672C;&#x8EAB;&#x7684;&#x4E00;&#x4E9B;&#x64CD;&#x4F5C;&#x65B9;&#x5F0F;&#xFF1A;&#x5C31;&#x50CF;&#x6570;&#x5B57;&#x7C7B;&#x578B;&#x7684;&#x7B97;&#x672F;&#x64CD;&#x4F5C;&#xFF0C;&#x5207;&#x7247;&#x7C7B;&#x578B;&#x7684;&#x53D6;&#x4E0B;&#x6807;&#x3001;&#x6DFB;&#x52A0;&#x5143;&#x7D20;&#x548C;&#x8303;&#x56F4;&#x83B7;&#x53D6;&#x64CD;&#x4F5C;&#x3002;&#x5177;&#x4F53;&#x7684;&#x7C7B;&#x578B;&#x8FD8;&#x53EF;&#x4EE5;&#x901A;&#x8FC7;&#x5B83;&#x7684;&#x5185;&#x7F6E;&#x65B9;&#x6CD5;&#x63D0;&#x4F9B;&#x989D;&#x5916;&#x7684;&#x884C;&#x4E3A;&#x64CD;&#x4F5C;&#x3002;&#x603B;&#x7684;&#x6765;&#x8BF4;&#xFF0C;&#x5F53;&#x4F60;&#x62FF;&#x5230;&#x4E00;&#x4E2A;&#x5177;&#x4F53;&#x7684;&#x7C7B;&#x578B;&#x65F6;&#x4F60;&#x5C31;&#x77E5;&#x9053;&#x5B83;&#x7684;&#x672C;&#x8EAB;&#x662F;&#x4EC0;&#x4E48;&#x548C;&#x4F60;&#x53EF;&#x4EE5;&#x7528;&#x5B83;&#x6765;&#x505A;&#x4EC0;&#x4E48;&#x3002;</p>
<p>&#x5728;Go&#x8BED;&#x8A00;&#x4E2D;&#x8FD8;&#x5B58;&#x5728;&#x7740;&#x53E6;&#x5916;&#x4E00;&#x79CD;&#x7C7B;&#x578B;&#xFF1A;&#x63A5;&#x53E3;&#x7C7B;&#x578B;&#x3002;&#x63A5;&#x53E3;&#x7C7B;&#x578B;&#x662F;&#x4E00;&#x79CD;&#x62BD;&#x8C61;&#x7684;&#x7C7B;&#x578B;&#x3002;&#x5B83;&#x4E0D;&#x4F1A;&#x66B4;&#x9732;&#x51FA;&#x5B83;&#x6240;&#x4EE3;&#x8868;&#x7684;&#x5BF9;&#x8C61;&#x7684;&#x5185;&#x90E8;&#x503C;&#x7684;&#x7ED3;&#x6784;&#x548C;&#x8FD9;&#x4E2A;&#x5BF9;&#x8C61;&#x652F;&#x6301;&#x7684;&#x57FA;&#x7840;&#x64CD;&#x4F5C;&#x7684;&#x96C6;&#x5408;&#xFF1B;&#x5B83;&#x4EEC;&#x53EA;&#x4F1A;&#x8868;&#x73B0;&#x51FA;&#x5B83;&#x4EEC;&#x81EA;&#x5DF1;&#x7684;&#x65B9;&#x6CD5;&#x3002;&#x4E5F;&#x5C31;&#x662F;&#x8BF4;&#x5F53;&#x4F60;&#x6709;&#x770B;&#x5230;&#x4E00;&#x4E2A;&#x63A5;&#x53E3;&#x7C7B;&#x578B;&#x7684;&#x503C;&#x65F6;&#xFF0C;&#x4F60;&#x4E0D;&#x77E5;&#x9053;&#x5B83;&#x662F;&#x4EC0;&#x4E48;&#xFF0C;&#x552F;&#x4E00;&#x77E5;&#x9053;&#x7684;&#x5C31;&#x662F;&#x53EF;&#x4EE5;&#x901A;&#x8FC7;&#x5B83;&#x7684;&#x65B9;&#x6CD5;&#x6765;&#x505A;&#x4EC0;&#x4E48;&#x3002;</p>
<p>&#x5728;&#x672C;&#x4E66;&#x4E2D;&#xFF0C;&#x6211;&#x4EEC;&#x4E00;&#x76F4;&#x4F7F;&#x7528;&#x4E24;&#x4E2A;&#x76F8;&#x4F3C;&#x7684;&#x51FD;&#x6570;&#x6765;&#x8FDB;&#x884C;&#x5B57;&#x7B26;&#x4E32;&#x7684;&#x683C;&#x5F0F;&#x5316;&#xFF1A;fmt.Printf&#xFF0C;&#x5B83;&#x4F1A;&#x628A;&#x7ED3;&#x679C;&#x5199;&#x5230;&#x6807;&#x51C6;&#x8F93;&#x51FA;&#xFF0C;&#x548C;fmt.Sprintf&#xFF0C;&#x5B83;&#x4F1A;&#x628A;&#x7ED3;&#x679C;&#x4EE5;&#x5B57;&#x7B26;&#x4E32;&#x7684;&#x5F62;&#x5F0F;&#x8FD4;&#x56DE;&#x3002;&#x5F97;&#x76CA;&#x4E8E;&#x4F7F;&#x7528;&#x63A5;&#x53E3;&#xFF0C;&#x6211;&#x4EEC;&#x4E0D;&#x5FC5;&#x53EF;&#x60B2;&#x7684;&#x56E0;&#x4E3A;&#x8FD4;&#x56DE;&#x7ED3;&#x679C;&#x5728;&#x4F7F;&#x7528;&#x65B9;&#x5F0F;&#x4E0A;&#x7684;&#x4E00;&#x4E9B;&#x6D45;&#x663E;&#x4E0D;&#x540C;&#x5C31;&#x5FC5;&#x9700;&#x628A;&#x683C;&#x5F0F;&#x5316;&#x8FD9;&#x4E2A;&#x6700;&#x56F0;&#x96BE;&#x7684;&#x8FC7;&#x7A0B;&#x590D;&#x5236;&#x4E00;&#x4EFD;&#x3002;&#x5B9E;&#x9645;&#x4E0A;&#xFF0C;&#x8FD9;&#x4E24;&#x4E2A;&#x51FD;&#x6570;&#x90FD;&#x4F7F;&#x7528;&#x4E86;&#x53E6;&#x4E00;&#x4E2A;&#x51FD;&#x6570;fmt.Fprintf&#x6765;&#x8FDB;&#x884C;&#x5C01;&#x88C5;&#x3002;fmt.Fprintf&#x8FD9;&#x4E2A;&#x51FD;&#x6570;&#x5BF9;&#x5B83;&#x7684;&#x8BA1;&#x7B97;&#x7ED3;&#x679C;&#x4F1A;&#x88AB;&#x600E;&#x4E48;&#x4F7F;&#x7528;&#x662F;&#x5B8C;&#x5168;&#x4E0D;&#x77E5;&#x9053;&#x7684;&#x3002;</p>
<pre><code class="lang-go"><span class="hljs-keyword">package</span> fmt

<span class="hljs-keyword">func</span> Fprintf(w io.Writer, format <span class="hljs-keyword">string</span>, args ...<span class="hljs-keyword">interface</span>{}) (<span class="hljs-keyword">int</span>, error)
<span class="hljs-keyword">func</span> Printf(format <span class="hljs-keyword">string</span>, args ...<span class="hljs-keyword">interface</span>{}) (<span class="hljs-keyword">int</span>, error) {
    <span class="hljs-keyword">return</span> Fprintf(os.Stdout, format, args...)
}
<span class="hljs-keyword">func</span> Sprintf(format <span class="hljs-keyword">string</span>, args ...<span class="hljs-keyword">interface</span>{}) <span class="hljs-keyword">string</span> {
    <span class="hljs-keyword">var</span> buf bytes.Buffer
    Fprintf(&amp;buf, format, args...)
    <span class="hljs-keyword">return</span> buf.String()
}
</code></pre>
<p>Fprintf&#x7684;&#x524D;&#x7F00;F&#x8868;&#x793A;&#x6587;&#x4EF6;&#xFF08;File&#xFF09;&#x4E5F;&#x8868;&#x660E;&#x683C;&#x5F0F;&#x5316;&#x8F93;&#x51FA;&#x7ED3;&#x679C;&#x5E94;&#x8BE5;&#x88AB;&#x5199;&#x5165;&#x7B2C;&#x4E00;&#x4E2A;&#x53C2;&#x6570;&#x63D0;&#x4F9B;&#x7684;&#x6587;&#x4EF6;&#x4E2D;&#x3002;&#x5728;Printf&#x51FD;&#x6570;&#x4E2D;&#x7684;&#x7B2C;&#x4E00;&#x4E2A;&#x53C2;&#x6570;os.Stdout&#x662F;<code>*os.File</code>&#x7C7B;&#x578B;&#xFF1B;&#x5728;Sprintf&#x51FD;&#x6570;&#x4E2D;&#x7684;&#x7B2C;&#x4E00;&#x4E2A;&#x53C2;&#x6570;&amp;buf&#x662F;&#x4E00;&#x4E2A;&#x6307;&#x5411;&#x53EF;&#x4EE5;&#x5199;&#x5165;&#x5B57;&#x8282;&#x7684;&#x5185;&#x5B58;&#x7F13;&#x51B2;&#x533A;&#xFF0C;&#x7136;&#x800C;&#x5B83;
&#x5E76;&#x4E0D;&#x662F;&#x4E00;&#x4E2A;&#x6587;&#x4EF6;&#x7C7B;&#x578B;&#x5C3D;&#x7BA1;&#x5B83;&#x5728;&#x67D0;&#x79CD;&#x610F;&#x4E49;&#x4E0A;&#x548C;&#x6587;&#x4EF6;&#x7C7B;&#x578B;&#x76F8;&#x4F3C;&#x3002;</p>
<p>&#x5373;&#x4F7F;Fprintf&#x51FD;&#x6570;&#x4E2D;&#x7684;&#x7B2C;&#x4E00;&#x4E2A;&#x53C2;&#x6570;&#x4E5F;&#x4E0D;&#x662F;&#x4E00;&#x4E2A;&#x6587;&#x4EF6;&#x7C7B;&#x578B;&#x3002;&#x5B83;&#x662F;io.Writer&#x7C7B;&#x578B;&#xFF0C;&#x8FD9;&#x662F;&#x4E00;&#x4E2A;&#x63A5;&#x53E3;&#x7C7B;&#x578B;&#x5B9A;&#x4E49;&#x5982;&#x4E0B;&#xFF1A;</p>
<pre><code class="lang-go"><span class="hljs-keyword">package</span> io

<span class="hljs-comment">// Writer is the interface that wraps the basic Write method.</span>
<span class="hljs-keyword">type</span> Writer <span class="hljs-keyword">interface</span> {
    <span class="hljs-comment">// Write writes len(p) bytes from p to the underlying data stream.</span>
    <span class="hljs-comment">// It returns the number of bytes written from p (0 &lt;= n &lt;= len(p))</span>
    <span class="hljs-comment">// and any error encountered that caused the write to stop early.</span>
    <span class="hljs-comment">// Write must return a non-nil error if it returns n &lt; len(p).</span>
    <span class="hljs-comment">// Write must not modify the slice data, even temporarily.</span>
    <span class="hljs-comment">//</span>
    <span class="hljs-comment">// Implementations must not retain p.</span>
    Write(p []<span class="hljs-keyword">byte</span>) (n <span class="hljs-keyword">int</span>, err error)
}
</code></pre>
<p>io.Writer&#x7C7B;&#x578B;&#x5B9A;&#x4E49;&#x4E86;&#x51FD;&#x6570;Fprintf&#x548C;&#x8FD9;&#x4E2A;&#x51FD;&#x6570;&#x8C03;&#x7528;&#x8005;&#x4E4B;&#x95F4;&#x7684;&#x7EA6;&#x5B9A;&#x3002;&#x4E00;&#x65B9;&#x9762;&#x8FD9;&#x4E2A;&#x7EA6;&#x5B9A;&#x9700;&#x8981;&#x8C03;&#x7528;&#x8005;&#x63D0;&#x4F9B;&#x5177;&#x4F53;&#x7C7B;&#x578B;&#x7684;&#x503C;&#x5C31;&#x50CF;<code>*os.File</code>&#x548C;<code>*bytes.Buffer</code>&#xFF0C;&#x8FD9;&#x4E9B;&#x7C7B;&#x578B;&#x90FD;&#x6709;&#x4E00;&#x4E2A;&#x7279;&#x5B9A;&#x7B7E;&#x540D;&#x548C;&#x884C;&#x4E3A;&#x7684;Write&#x7684;&#x51FD;&#x6570;&#x3002;&#x53E6;&#x4E00;&#x65B9;&#x9762;&#x8FD9;&#x4E2A;&#x7EA6;&#x5B9A;&#x4FDD;&#x8BC1;&#x4E86;Fprintf&#x63A5;&#x53D7;&#x4EFB;&#x4F55;&#x6EE1;&#x8DB3;io.Writer&#x63A5;&#x53E3;&#x7684;&#x503C;&#x90FD;&#x53EF;&#x4EE5;&#x5DE5;&#x4F5C;&#x3002;Fprintf&#x51FD;&#x6570;&#x53EF;&#x80FD;&#x6CA1;&#x6709;&#x5047;&#x5B9A;&#x5199;&#x5165;&#x7684;&#x662F;&#x4E00;&#x4E2A;&#x6587;&#x4EF6;&#x6216;&#x662F;&#x4E00;&#x6BB5;&#x5185;&#x5B58;&#xFF0C;&#x800C;&#x662F;&#x5199;&#x5165;&#x4E00;&#x4E2A;&#x53EF;&#x4EE5;&#x8C03;&#x7528;Write&#x51FD;&#x6570;&#x7684;&#x503C;&#x3002;</p>
<p>&#x56E0;&#x4E3A;fmt.Fprintf&#x51FD;&#x6570;&#x6CA1;&#x6709;&#x5BF9;&#x5177;&#x4F53;&#x64CD;&#x4F5C;&#x7684;&#x503C;&#x505A;&#x4EFB;&#x4F55;&#x5047;&#x8BBE;&#xFF0C;&#x800C;&#x662F;&#x4EC5;&#x4EC5;&#x901A;&#x8FC7;io.Writer&#x63A5;&#x53E3;&#x7684;&#x7EA6;&#x5B9A;&#x6765;&#x4FDD;&#x8BC1;&#x884C;&#x4E3A;&#xFF0C;&#x6240;&#x4EE5;&#x7B2C;&#x4E00;&#x4E2A;&#x53C2;&#x6570;&#x53EF;&#x4EE5;&#x5B89;&#x5168;&#x5730;&#x4F20;&#x5165;&#x4E00;&#x4E2A;&#x53EA;&#x9700;&#x8981;&#x6EE1;&#x8DB3;io.Writer&#x63A5;&#x53E3;&#x7684;&#x4EFB;&#x610F;&#x5177;&#x4F53;&#x7C7B;&#x578B;&#x7684;&#x503C;&#x3002;&#x4E00;&#x4E2A;&#x7C7B;&#x578B;&#x53EF;&#x4EE5;&#x81EA;&#x7531;&#x5730;&#x88AB;&#x53E6;&#x4E00;&#x4E2A;&#x6EE1;&#x8DB3;&#x76F8;&#x540C;&#x63A5;&#x53E3;&#x7684;&#x7C7B;&#x578B;&#x66FF;&#x6362;&#xFF0C;&#x88AB;&#x79F0;&#x4F5C;&#x53EF;&#x66FF;&#x6362;&#x6027;&#xFF08;LSP&#x91CC;&#x6C0F;&#x66FF;&#x6362;&#xFF09;&#x3002;&#x8FD9;&#x662F;&#x4E00;&#x4E2A;&#x9762;&#x5411;&#x5BF9;&#x8C61;&#x7684;&#x7279;&#x5F81;&#x3002;</p>
<p>&#x8BA9;&#x6211;&#x4EEC;&#x901A;&#x8FC7;&#x4E00;&#x4E2A;&#x65B0;&#x7684;&#x7C7B;&#x578B;&#x6765;&#x8FDB;&#x884C;&#x6821;&#x9A8C;&#xFF0C;&#x4E0B;&#x9762;<code>*ByteCounter</code>&#x7C7B;&#x578B;&#x91CC;&#x7684;Write&#x65B9;&#x6CD5;&#xFF0C;&#x4EC5;&#x4EC5;&#x5728;&#x4E22;&#x5F03;&#x5199;&#x5411;&#x5B83;&#x7684;&#x5B57;&#x8282;&#x524D;&#x7EDF;&#x8BA1;&#x5B83;&#x4EEC;&#x7684;&#x957F;&#x5EA6;&#x3002;&#xFF08;&#x5728;&#x8FD9;&#x4E2A;+=&#x8D4B;&#x503C;&#x8BED;&#x53E5;&#x4E2D;&#xFF0C;&#x8BA9;len(p)&#x7684;&#x7C7B;&#x578B;&#x548C;<code>*c</code>&#x7684;&#x7C7B;&#x578B;&#x5339;&#x914D;&#x7684;&#x8F6C;&#x6362;&#x662F;&#x5FC5;&#x987B;&#x7684;&#x3002;&#xFF09;</p>
<p><u><i>gopl.io/ch7/bytecounter</i></u></p>
<pre><code class="lang-go"><span class="hljs-keyword">type</span> ByteCounter <span class="hljs-keyword">int</span>

<span class="hljs-keyword">func</span> (c *ByteCounter) Write(p []<span class="hljs-keyword">byte</span>) (<span class="hljs-keyword">int</span>, error) {
    *c += ByteCounter(<span class="hljs-built_in">len</span>(p)) <span class="hljs-comment">// convert int to ByteCounter</span>
    <span class="hljs-keyword">return</span> <span class="hljs-built_in">len</span>(p), <span class="hljs-literal">nil</span>
}
</code></pre>
<p>&#x56E0;&#x4E3A;*ByteCounter&#x6EE1;&#x8DB3;io.Writer&#x7684;&#x7EA6;&#x5B9A;&#xFF0C;&#x6211;&#x4EEC;&#x53EF;&#x4EE5;&#x628A;&#x5B83;&#x4F20;&#x5165;Fprintf&#x51FD;&#x6570;&#x4E2D;&#xFF1B;Fprintf&#x51FD;&#x6570;&#x6267;&#x884C;&#x5B57;&#x7B26;&#x4E32;&#x683C;&#x5F0F;&#x5316;&#x7684;&#x8FC7;&#x7A0B;&#x4E0D;&#x4F1A;&#x53BB;&#x5173;&#x6CE8;ByteCounter&#x6B63;&#x786E;&#x7684;&#x7D2F;&#x52A0;&#x7ED3;&#x679C;&#x7684;&#x957F;&#x5EA6;&#x3002;</p>
<pre><code class="lang-go"><span class="hljs-keyword">var</span> c ByteCounter
c.Write([]<span class="hljs-keyword">byte</span>(<span class="hljs-string">&quot;hello&quot;</span>))
fmt.Println(c) <span class="hljs-comment">// &quot;5&quot;, = len(&quot;hello&quot;)</span>
c = <span class="hljs-number">0</span>          <span class="hljs-comment">// reset the counter</span>
<span class="hljs-keyword">var</span> name = <span class="hljs-string">&quot;Dolly&quot;</span>
fmt.Fprintf(&amp;c, <span class="hljs-string">&quot;hello, %s&quot;</span>, name)
fmt.Println(c) <span class="hljs-comment">// &quot;12&quot;, = len(&quot;hello, Dolly&quot;)</span>
</code></pre>
<p>&#x9664;&#x4E86;io.Writer&#x8FD9;&#x4E2A;&#x63A5;&#x53E3;&#x7C7B;&#x578B;&#xFF0C;&#x8FD8;&#x6709;&#x53E6;&#x4E00;&#x4E2A;&#x5BF9;fmt&#x5305;&#x5F88;&#x91CD;&#x8981;&#x7684;&#x63A5;&#x53E3;&#x7C7B;&#x578B;&#x3002;Fprintf&#x548C;Fprintln&#x51FD;&#x6570;&#x5411;&#x7C7B;&#x578B;&#x63D0;&#x4F9B;&#x4E86;&#x4E00;&#x79CD;&#x63A7;&#x5236;&#x5B83;&#x4EEC;&#x503C;&#x8F93;&#x51FA;&#x7684;&#x9014;&#x5F84;&#x3002;&#x5728;2.5&#x8282;&#x4E2D;&#xFF0C;&#x6211;&#x4EEC;&#x4E3A;Celsius&#x7C7B;&#x578B;&#x63D0;&#x4F9B;&#x4E86;&#x4E00;&#x4E2A;String&#x65B9;&#x6CD5;&#x4EE5;&#x4FBF;&#x4E8E;&#x53EF;&#x4EE5;&#x6253;&#x5370;&#x6210;&#x8FD9;&#x6837;&quot;100&#xB0;C&quot; &#xFF0C;&#x5728;6.5&#x8282;&#x4E2D;&#x6211;&#x4EEC;&#x7ED9;*IntSet&#x6DFB;&#x52A0;&#x4E00;&#x4E2A;String&#x65B9;&#x6CD5;&#xFF0C;&#x8FD9;&#x6837;&#x96C6;&#x5408;&#x53EF;&#x4EE5;&#x7528;&#x4F20;&#x7EDF;&#x7684;&#x7B26;&#x53F7;&#x6765;&#x8FDB;&#x884C;&#x8868;&#x793A;&#x5C31;&#x50CF;&quot;{1 2 3}&quot;&#x3002;&#x7ED9;&#x4E00;&#x4E2A;&#x7C7B;&#x578B;&#x5B9A;&#x4E49;String&#x65B9;&#x6CD5;&#xFF0C;&#x53EF;&#x4EE5;&#x8BA9;&#x5B83;&#x6EE1;&#x8DB3;&#x6700;&#x5E7F;&#x6CDB;&#x4F7F;&#x7528;&#x4E4B;&#x4E00;&#x7684;&#x63A5;&#x53E3;&#x7C7B;&#x578B;fmt.Stringer&#xFF1A;</p>
<pre><code class="lang-go"><span class="hljs-keyword">package</span> fmt

<span class="hljs-comment">// The String method is used to print values passed</span>
<span class="hljs-comment">// as an operand to any format that accepts a string</span>
<span class="hljs-comment">// or to an unformatted printer such as Print.</span>
<span class="hljs-keyword">type</span> Stringer <span class="hljs-keyword">interface</span> {
    String() <span class="hljs-keyword">string</span>
}
</code></pre>
<p>&#x6211;&#x4EEC;&#x4F1A;&#x5728;7.10&#x8282;&#x89E3;&#x91CA;fmt&#x5305;&#x600E;&#x4E48;&#x53D1;&#x73B0;&#x54EA;&#x4E9B;&#x503C;&#x662F;&#x6EE1;&#x8DB3;&#x8FD9;&#x4E2A;&#x63A5;&#x53E3;&#x7C7B;&#x578B;&#x7684;&#x3002;</p>
<p><strong>&#x7EC3;&#x4E60; 7.1&#xFF1A;</strong> &#x4F7F;&#x7528;&#x6765;&#x81EA;ByteCounter&#x7684;&#x601D;&#x8DEF;&#xFF0C;&#x5B9E;&#x73B0;&#x4E00;&#x4E2A;&#x9488;&#x5BF9;&#x5355;&#x8BCD;&#x548C;&#x884C;&#x6570;&#x7684;&#x8BA1;&#x6570;&#x5668;&#x3002;&#x4F60;&#x4F1A;&#x53D1;&#x73B0;bufio.ScanWords&#x975E;&#x5E38;&#x7684;&#x6709;&#x7528;&#x3002;</p>
<p><strong>&#x7EC3;&#x4E60; 7.2&#xFF1A;</strong> &#x5199;&#x4E00;&#x4E2A;&#x5E26;&#x6709;&#x5982;&#x4E0B;&#x51FD;&#x6570;&#x7B7E;&#x540D;&#x7684;&#x51FD;&#x6570;CountingWriter&#xFF0C;&#x4F20;&#x5165;&#x4E00;&#x4E2A;io.Writer&#x63A5;&#x53E3;&#x7C7B;&#x578B;&#xFF0C;&#x8FD4;&#x56DE;&#x4E00;&#x4E2A;&#x628A;&#x539F;&#x6765;&#x7684;Writer&#x5C01;&#x88C5;&#x5728;&#x91CC;&#x9762;&#x7684;&#x65B0;&#x7684;Writer&#x7C7B;&#x578B;&#x548C;&#x4E00;&#x4E2A;&#x8868;&#x793A;&#x65B0;&#x7684;&#x5199;&#x5165;&#x5B57;&#x8282;&#x6570;&#x7684;int64&#x7C7B;&#x578B;&#x6307;&#x9488;&#x3002;</p>
<pre><code class="lang-go"><span class="hljs-keyword">func</span> CountingWriter(w io.Writer) (io.Writer, *<span class="hljs-keyword">int64</span>)
</code></pre>
<p><strong>&#x7EC3;&#x4E60; 7.3&#xFF1A;</strong> &#x4E3A;&#x5728;gopl.io/ch4/treesort&#xFF08;&#xA7;4.4&#xFF09;&#x4E2D;&#x7684;*tree&#x7C7B;&#x578B;&#x5B9E;&#x73B0;&#x4E00;&#x4E2A;String&#x65B9;&#x6CD5;&#x53BB;&#x5C55;&#x793A;tree&#x7C7B;&#x578B;&#x7684;&#x503C;&#x5E8F;&#x5217;&#x3002;</p>

                                
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